It is the summer of 1883 and Professor Langdon St. Ives, brilliant but eccentric scientist and explorer, is at home in Aylesford with his family. A few miles to the north a steam launch has been taken by pirates above Egypt Bay, the crew murdered and pitched overboard.

In Aylesford itself a grave is opened and possibly robbed of the skull. The suspected grave robber, the infamous Dr. Ignacio Narbondo, is an old nemesis of Langdon St. Ives. When Dr. Narbondo returns to kidnap his four-year-old son Eddie and then vanishes into the night, St. Ives and his factotum Hasbro race into London in pursuit...